Process of producing carbon-free ferrochromium.



" v UNITED AT PATENT OFFICE I name oonnsclmm'r Am) or'ro wmnor E-SSEN-ON-THE-BIUHVB, GERMANY, assmnons .zl'o eonnscmumr rnnnmrrcomranx, on NEW YORK, N. Y., a conrona'rxon or NEW YORK.

'rnoczss or rnonucmo cannon-FREE, rnnnocnnomxom.

No Drawing.

,To all whom it may concern Be it known that W6,'IIANS Gonoscmum'r andjo'r'ro WEIL, subjects of the King of Prussia, German Emperor, and residents of Essen-on-the-Ruhr, in the Province of the Rhine, German Empire, have jointly invented certain new and useful Improvements in Processes of Producing Carbon- -Free Ferrochromium, of which the follow- 10 ing is a spe'c'ification- Carbon-free ferro-chromium cannot be manufactured in electrical furnaces, but

only by means of the aluminothermic-process. As the yields obtained by this process are, however, comparativel unfavorable, the price of the carbon-free erro-chromium is relatively high.

If chrome-iron ore which as is well known consists essentially of chromic oxid and ferric oxid or ferrous oxid is subjected to the aluminothermic reaction, the best result to be obtained, even when using a material of high percentage and working strictly according to the rules of the art, will give a ferro-chromium with a yield of about 70 per cent. of the chromium contained in the raw material. Furthermore another disadvantage arises from the fact that it is not I, possibleto always obtain perfectly uniform results, even when using the same raw material. The reason for this peculiar fact seems'to be a dissociation taking place within thealuminothermic mixture when burning.

' Now it has been found that it is possible to highly'increase the yield of chromium from chrome-iron ore, as well as to always obtain uniform iron-chromium alloys by adding a certain percentage of oxid of chromlum to the mixture of chrome-iron 40 ore and aluminum or other reducing metal, and then subjecting this mixture to the aluminothermic reaction. By this process it is ossibleto increase the yield of chromium rom chrome-iron ore up to about 15 to 20 per cent and at the same time to produce ferro-chromium of a uniform composition. The amount of the addition of chromic oxid which of course also increases the per Specification of Letters Patent.

- preferably up to red heat and then to the chromium in-the aluminothermic manufac- In witness whereof we have hereunto set Patented Apr. 20, 1915.

' Application filed October 29,1912. seria11wc;72s,45o.

'centage of chromium in-the alloy produced may be suitably chosen according to the per: 50

' centage of chromium desired in the ferrochromium to be produced.

In the preferred form of carrying out the invention the mixture of-chrome-iron ore, chromic oxid and aluminum, (or other re ducing metals) is, with a view to further increasing the yield, subjected to a preheating process up to temperatures nearthe smelting point of the reducing metal and aluminothermic reaction.

What We claim is:

1. A process for increasing the yield'of ture of ferro-chromium from materials con- .taining chromium which consists in adding certain amount of;chromium oxid and subjecting thismass to the aluminothermic reaction.

2. A process for 'increasing the yield of chromium in the aluminothermic manufacture of ferro-chromium from chrome-iron ore which consists in adding to the ordinary aluminothermic mixture of chrome-iron ore and reducing metal a 'certain amount of chromic oxid, preheating the mixture up to a temperature near the melting point of the reducing metal and subjecting this mass to the aluminothermic reaction.

3. A process for increasing the yield of chromium in the aluminothermic manufacture of ferro-chromium from chrome iron orewhich consists in adding to the ordinary aluminothermic mixture of chrome-iron ore and reducing metal a certain amount of chromic oxid, preheating the mixture up. to red heat and subjecting this mass to the aluminothermic reaction.-

our hands in. the presence of two witn. HANS GOLDSCHMIDT. {14.8.1

OTTO W'EHJ. 1 1.5.] V

In the preselnce of;

HELEN 

